We are studying the structure and function of several regulatory genes of E. coli: adenylate cyelase (cya), crp, rho, and nus. They regulate transcription initiation and termination of a wide variety of other operons. In order to study how these genes are themselves regulated in vivo, we have fused the control regions (promoter, operator, etc) of cya, crp, and rho genes to the gene of Beta-galactosidase, which can be assayed easily. Assay of the latter enzyme in these fusion strains under a variety of conditions demonstrated that all the three genes are autogenously regulated. We have also cloned the cya, crp, rho, and nus genes into phage vectors. In vitro study of the regulation of these genes using the DNA clones and purified proteins are in progress.